The invention relates in general to contaminated earth treatment and in particular to a new and useful process for the treating of contaminated earth by homogenizing and comminuting the material and adding water and thereafter treating the water suspension by drying it and separating dissolved substances.
According to the invention contaminated earth, in particular earth from coking plants or plants with similar products is treated. This earth is usually contaminated with various anorganic and organic substances, such as benzene, toluene, naphthalene, phenols and other mon- and polycyclic or aliphatic oxygen-, nitrogen- and sulphur-containing hydrocarbon compounds as well as simple and complex inorganic or organic salts.
From German OS No. 32 16 771 a process for the cleaning of earth contaminated with toxic material is known, wherein the earth is e.g. heated in a rotating drum and the resulting gas products are burnt.
German patent application No. P34 47 079 also refers to a process for the thermal treatment of contaminated earth. Herein the earth is treated at a temperature cf at least 600.degree. C. and the resulting gas is also burnt. In the two cited processes, the gas contaminants are removed from the earth by means of thermal treatment at relatively high temperatures. For this purpose a relatively large amount of energy is required.
German Os No. 25 31 732 describes a process for the removal, treatment and regeneration of oil-polluted earth. Herein the oil and the water-soluble noxious components are washed out in low surface tension water preferably at temperatures between 60.degree. and 90.degree. C. Herein the comminuted material to be treated is intensively mixed with the cleaning medium in a spiral drum and then separated from the pollutant-binding cleaning medium by sedimentation in a clearing sump.
A similar process for the regeneration of earth, contaminated in particular by oil is known from German OS No. 27 24 271. Herein the contaminated earth is suspended [slurry] possibly after comminution, in a liquid, e.g. water and then heated to vaporizing temperature in a continuous flow chamber. The upper layer of the suspension is stripped off and separated in the continuous flow chamber. It has been proven that the substances dissolved are not washed out from the contaminated earth in such a process at the vaporization temperature of water.